There is "accumulating evidence" linking the Zika virus to microcephaly and Guillain-Barre syndrome, the World Health Organization (WHO) says.

There is "accumulating evidence" of a link between the Zika virus and two neurologicaldisorders, microcephaly and Guillain-Barre syndrome, the World Health Organization (WHO) said on Friday (March 4).

The WHO's Emergency Committee will meet next week to review "evolving information" and its recommendations on travel and trade in what is thought to be high season for transmission of the mosquito-borne virus in the southern hemisphere, it said.

Dr. Bruce Aylward, WHO Executive Director for Outbreaks and Health Emergencies, said that recently published studies in the Lancet on microcephaly and by the U.S. Centers for Disease Control (CDC) on Guillain-Barre had strengthened the case that the Zika virus is responsible.

"Since the public health emergency of international concern was declared back in February, the evidence that there maybe a causal relationship has continued to accumulate and as importantly we have not seen the counter factual, the fact that there's evidence it's due to something else, certainly not at this point," Aylward told a news briefing in Geneva.

French scientists, in a retrospective study of a Zika outbreak in French Polynesia in 2013-2014, said last week they had proved a link between Zika and Guillain-Barre, suggesting countries hit by the Zika epidemic will see a rise in cases of the serious neurological condition.

Aylward said that in light of the accumulation of evidence, a panel of experts would be convened next week.

"The other thing that we are doing next week is convening the emergency committee on Zikaand on microcephaly under the international health regulations to review the upcoming, the evolving information again, look at the status of the public health emergency of international concern, recommendations around travel and trade, and then most, most importantly the recommendations around coordinated international action given the further evolving information," he said.

A study of nine pregnant women from the United States who travelled to countries where theZika virus was circulating showed a greater-than-expected number of fetal infections and brain abnormalities, U.S. health officials said last week.

Much remains unknown about Zika, including whether the virus actually causes microcephaly in babies.

Brazil said it has confirmed more than 640 cases of microcephaly, and considers most of them to be related to Zika infections in the mothers. Brazil is investigating more than 4,200 additional suspected cases of microcephaly.

"We are now in the high season for dengue virus transmission in the southern hemisphere that started as you know a month or so ago. We believe, because it is the same vector, that this would be the high season obviously for Zika transmission as well," Aylward said.

Zika was first identified in 1947 in Uganda and previously linked to smaller outbreaks. Many people who are infected show no symptoms, while those who become ill report relatively mild effects of rash or fever. There is no vaccine or treatment for the virus, which is in the same family as dengue, West Nile virus and yellow fever.